The present invention relates to a device for insulating vibrations and supporting a vibration generating means such as an engine of a vehicle, and particularly to a fluid sealed type vibration insulating device which has a fluid chamber defined by the elastic support and is arranged to sufficiently decrease a magnitude vibration input. The present invention more particularly relates to a movable plate partly defining the fluid chamber, which is displaced in the direction for changing the volume of the fluid chamber.
As one example, Japanese Patent Kokai No. 5-332392 discloses a fluid sealed type vibration insulating device which is able to generate an active supporting force. This vibration insulating device is provided with an inner cylinder fixed to one of a vibrating means and a structural member, an outer cylinder fixed to the other one of the vibrating means and the structural member while surrounding the inner cylinder, an elastic support disposed between the inner and outer cylinders, a main fluid chamber defined by the elastic support, an auxiliary fluid chamber variable in volume, an orifice communicating the main fluid chamber and the auxiliary fluid chamber, fluid sealed in the main fluid chamber, the auxiliary fluid chamber and the orifice, a movable plate displaceable in the direction for changing the volume of the main fluid chamber, and an actuator driven by the movable plate. This conventional vibration insulating device is arranged to generate a desired damping force by flowing the fluid through the orifice and to generate an active supporting force by elastically deforming an expanding directional functioning spring of the elastic support due to the displacement of the movable plate.